Needle selection device in a circular knitting machine with elastic jacks

Abstract

A device for selecting needles in a circular knitting machine of the elastic jack type, comprising auxiliary jacks positioned below and in the same tricks as the elastic jacks. The auxiliary jacks are selected electromagnetically so that they act to radially lock the elastic jacks while these are in their flexed position within the tricks so that they cannot return outwards and thus engage their raising cams and activate their needle.

I claim: 
     
       1. A device for selecting needles in a circular knitting machine having a needle cylinder, comprising: a) a first jack for activating a corresponding needle, wherein said first jack is slidably housed in a groove of the cylinder;   b) a first cam for moving said first jack between an active and inactive position;   c) a second jack corresponding to said first jack, wherein said second jack is slidably housed in the same groove as corresponding first jack, wherein said second jack engages the corresponding first jack when said first jack is held in said inactive position, and wherein said second jack comprises: 1. a rigid portion for moving axially in the grove; and   2) a flexible portion for moving axially in the groove and for moving radially with respect to the needle cylinder;     d) a first contour for providing said radial movement of said flexible portion to a radial position;   e) a second contour spaced apart from said first contour for proving said axial movement of said flexible portion of said second jack and said engagement with the corresponding first jack; and   f) actuation means interposed between said first contour and said second contour for retaining said flexible portion in said radial position so that when said first jack activates a corresponding needle said flexible portion is not engaged by said second contour so that said second jack does not axially move and does not engage the corresponding first jack.   
     
     
       2. The device of claim 1, wherein said actuation means comprises: a) a ferromagnetic plate having two peripheral members extending opposite one another and a central member therebetween, wherein said central member is separated from said peripheral members by diamagnetic material;   b) a permanent magnet positioned on said plate and connecting said peripheral members for attracting said flexible portion, wherein said permanent magnet has a bore therethrough; and   c) an electromagnet operatively associated with said central member for applying magnetic polarity thereto.   
     
     
       3. The device of claim 2, wherein said actuation means further comprises an antiwear covering for reducing wear when cooperating with said flexible portion. 
     
     
       4. The device of claim 3, wherein the profile of said flexible portion of one second jack differs from the profile of said flexible portion of another second jack in the knitting machine. 
     
     
       5. The device of claim 3, wherein said flexible portion of said second jack comprises at least one projection, wherein said projection of said flexible portion of one second jack differs from said projection of said flexible portion of another second jack. 
     
     
       6. The device of claim 3, wherein said flexible portion of said second jack comprises at least one recess, wherein said recess of said flexible portion of one second jack differs from said recess of said flexible portion of another second jack. 
     
     
       7. The device of claim 4, further comprising a plurality of said actuation means, wherein each of said actuation means is selectively located for corresponding with said profile of said flexible portion. 
     
     
       8. The device of claim 3, further comprising a plurality of second jacks having a first length positioned on a first ring structure of the knitting machine and a plurality of second jacks having a second length positioned on a second ring structure of the knitting machine, wherein said first ring structure and said second ring structure are concentric, and further comprising a first cam ring cooperating with said plurality of second jacks having said first length and a second cam ring cooperating with said plurality of second jacks having said second length. 
     
     
       9. The device of claim 8, wherein said plurality of second jacks having a first length and said plurality of second jacks having a second length have profiles which differ one from another. 
     
     
       10. The device of claim 3, wherein said first cam ring and said second cam ring and said actuation devices are located on different levels in the knitting machine. 
     
     
       11. The device of claim 3, wherein said applied magnetic polarity differs from the magnetic polarity of said permanent magnet for releasing said flexible portion attracted by said permanent magnet. 
     
     
       12. The device of claim 3, wherein said applied magnetic polarity is the same polarity as said permanent magnet for attracting said flexible portion. 
     
     
       13. The device of claim 3, wherein said second jack is adapted to engage said first jack for retaining said first jack in said inactive position as said first cam urges said first jack into said inactive position.